I want to make a ceramic sculpture where the head rotates 180 degrees
(either at intervals or when a loud sound happens). I am not sure how
to do it or where to even start researching. 
I might make the head out of something other than clay, so it doesnot
weigh so much.
I need to know what I need to read, if there are books about it. Or
where I can buy mechanisms for something like that. Are there
specialty stores? I live in New York City.

You could try taking apart an existing machine that responds to sound
and using the components (dancing santa, dancing flower). Since you
simply want a rotational movement this would be the easiest as you
will only need one motor.

For more precise control (number of rotations before stopping,
rotations at set intervals, etc, you will need a motor control
circuit. They are sold all over the internet, and even can be
programmed from your computer.